We propose to study the mechanism by which the enzyme asparaginase works in order to better understand the effect of the enzyme on leukemia. We will search for an acyl enzyme intermediate or an anhydride intermediate by use of various substrate analogs. We will use rapid kinetics, isotope effects, and isotope exchange to probe the kinetic mechanism. We will search for other substrates and other reactions catalyzed by the enzyme in order to determine the mechanism of action of the enzyme and in order to ascertain the possible role of such reactions in leukemia therapy.